dll中全局变量在外部进行引用

在Windows中实际导出全局变量，您必须使用类似于export / import语法的语法，例如：

 #ifdef COMPILING_THE_DLL
 #define MY_DLL_EXPORT extern "C" __declspec(dllexport)
 #else
 #define MY_DLL_EXPORT extern "C" __declspec(dllimport)
 #endif

 MY_DLL_EXPORT int my_global;

参考网址：

https://codeday.me/bug/20170811/55724.html

https://blog.csdn.net/mangobar/article/details/53390552

https://blog.csdn.net/silvervi/article/details/5055707